1. Field of the Invention
This invention relates to a double ranging drum cutter having a bedrock sensor based on a video image processing system and, more particularly, to a double ranging drum cutter of long wall type for coal extraction in which the boundary between a coal layer and bedrock over or under the coal layer can be readily judged in an atmosphere containing a great quantity of mine dust, therby permitting the cutting of a large quantity coal layer without cutting much bedrock.
2. Description of the Prior Art
Present day coal mines make use of a double ranging drum cutter that is used for long wall type coal extraction. This machine includes a drum cutter body which is moved along a coal layer under the guide of a face conveyor, a drum support arm rotatably mounted by a transversal shaft on each end of the drum cutter body in the direction of movement thereof, an arm driver for rotating each of the arms, and a cutter drum mounted on the end of each arm and driven by a drum driver.
When the double ranging drum cutter is operated for long wall type coal extraction, the operator judges whether the cutter drum is cutting a coal layer of the bedrock from vibrations of the drum cutter body, sparks, noise or the like produced as the cutter drum is cutting the bedrock in contact therewith.
However, it is difficult to make an accurate determination in an atmosphere containing a great quantity of floating mine dust as to whether a boundary between a coal layer and bedrock is being cut with the man's five senses. Also, it is difficult to have quantitative knowledge of the ratio of the area of a bedrock to the area of a coal layer in a portion of the bedrock being cut.
If the area of the bedrock in a portion of the bedrock being cut is excessive, early wear of the pick in the cutter drum results because the bedrock is hard. On the other hand, if no bedrock is cut at all, a comparatively great quantity of coal will remain unextracted adjacent to the bedrock, so that the coal extraction efficiency is low.